Format Converter
FFmpeg PoweredConvert between MP4, WebM, AVI, MOV formats
Drag & drop files here, or click to select
Supports MP4, WebM, AVI, MOV, MKV and other common formatsHow to Use
- Click the area above to select a file, or drag and drop a file onto the page
- Adjust parameters in the settings area
- Click the process button and download the result when ready
Frequently Asked Questions
How It Works
The Format Converter uses FFmpeg WebAssembly with its full suite of video and audio codecs to re-mux or re-encode media files between container formats. The tool supports MP4 (H.264/AAC), WebM (VP8/VP9/Opus), AVI (various), and MOV (QuickTime) containers.
When converting between compatible codecs (e.g., H.264 in MP4 to H.264 in MOV), the tool uses stream copying (-c copy) which simply moves the video and audio streams to a new container — this is instant and lossless. When codec conversion is required (e.g., VP9 to H.264), the full encoding pipeline is activated: the video is decoded frame-by-frame using the source codec and re-encoded using the target codec with your specified quality settings.
The WebAssembly FFmpeg binary handles all container muxing operations including subtitle tracks, chapter metadata, and stream disposition flags. The entire pipeline runs in a Web Worker, with progress callbacks reporting encoding speed in frames-per-second and estimated time remaining.
Tips & Best Practices
- Match codecs when possible: Converting MP4 to WebM with the same H.264 video stream can be done via copy mode, but changing the video codec requires re-encoding.
- Choose MP4 for universal compatibility — it plays on virtually every device, browser, and platform without issues.
- Use WebM for web delivery: WebM files are typically 10-20% smaller than MP4 at equivalent quality, making them ideal for web streaming.
- Preserve audio quality: When converting, select AAC at 192kbps or higher for MP4, or Opus at 128kbps for WebM.
- Avoid double-conversion: Don't convert from a lossy format to another lossy format if you can avoid it — each conversion adds generation loss.
- Check file size after conversion. If it's larger, the original format was already well-optimized — consider keeping it as-is.
Use Cases
Web developers converting MOV screen recordings to optimized WebM for faster page loading. Social media managers transforming AVI desktop captures to MP4 for cross-platform upload compatibility.
Podcast producers converting WAV studio recordings to MP3 or AAC for distribution. Video editors transcoding ProRes footage to H.264 for client review. Education platforms standardizing mixed-format video libraries to a single format for consistent playback. Mobile users converting large MOV files from iPhone to smaller MP4 for sharing via messaging apps.